A complete fs-laser-ablation route to miniaturized single-crystal PMN-PT piezoelectric actuators

This article presents a novel fabrication route for miniaturized piezoelectric actuators that relies exclusively on processes based on femtosecond (fs) laser ablation. Previous work has already demonstrated that fs-lasers are uniquely suited for the fabrication of piezoelectric actuators based on PMN-PT, which are required for multiaxial strain-tuning of quantum dots (QDs) to enable, e.g. the generation of highly entangled photon pairs. Building on these foundations, the present work advances actuator performance and capabilities by introducing a local thinning strategy. This approach allows the realization of smaller devices, which in turn enables lower operating voltages, while simultaneously offering the possibility of integrating multiple quantum light sources on a single chip. The article provides a detailed description of the full fabrication chain, entirely based on fs-laser processing steps, from substrate thinning to metal layer structuring and final device definition. A particular focus is placed on the final cutting process, where the implementation of a third-harmonic ultraviolet (UV) fs-laser wavelength significantly improves edge quality and shape definition compared to the second harmonic (SH) wavelength used in previous work. The device fabricated through the combination of local thinning and UV-based cutting promises not only to enhance the efficiency of strain transfer but also to ensure the mechanical stability required for practical applications. These results establish fs-laser-based fabrication as a versatile and scalable method for next-generation piezoelectric actuators, paving the way for advanced strain-engineering approaches in semiconductor quantum optics and integrated quantum photonics. • Fully Laser-Based Fabrication Workflow for PMN-PT actuators , The study introduces a complete process chain for actuator fabrication using only femtosecond (fs) laser ablation—covering substrate thinning, electrode structuring, and final device cutting—eliminating the need for conventional etching or lithography. • Local Thinning Strategy for Miniaturization , A novel approach of localized thinning reduces actuator size while maintaining mechanical stability. This enables higher electric fields at lower voltages and enables higher integration density. • UV fs-Laser Cutting for Precision , Switching from second harmonic (523 nm) to third harmonic UV wavelength (348 nm) significantly improves edge quality and cut resolution. This allows inter-arm distances as small as 5 µm, enhancing strain transfer and reducing operating voltage. • Optimized Surface and Conductivity , Advanced scanning strategies (random and small-to-large patterns) minimize roughness and defects in thinned cavities. Tests confirm reliable metal layer conductivity across non-planar surfaces, essential for actuator performance. • Impact on Quantum Photonics , The miniaturized actuators enable multiaxial strain-tuning of quantum dots, paving the way for scalable integration of quantum light sources and improved generation of entangled photons for next-generation quantum photonic devices.